One of these days, when I've been away from the CRT/TFT enough to recover some semblance of humanity, I shall surf the web for nice block diagrams and further my knowlege of it all. From my purely EE background, it seems like the same physical medium should be able to support the same bandwidth regardless of the direction. But, being a good little mailing list reader, I won't take up bandwidth on this mailing list to ask for stuff I can find one the web some day. Thank you anyway!
Fred -------------------------------------------------------------------------- Fred Ma Department of Electronics Carleton University, Mackenzie Building 1125 Colonel By Drive Ottawa, Ontario Canada K1S 5B6 [EMAIL PROTECTED] ========================================================================== > > Fred, > > Modems do more than just modulate and demodulate signals onto and from > analog wires. They also packetise, compress and error check the data. When > two modems communicate over the regular telephone system, the data is > packetised, compressed, checksummed, and converted to analog. At the other > end it is converted from analog to digital, error-checked, decompressed and > depacketised. > > The Kflex and V90 standards used the best analog to analog modem standards, > and removed the digital to analog conversion at the ISDN head end (it still > has to be packetised compressed and checksummed). Theoretically the ISDN > side should be transmitting at 64kbps because that is the bandwidth of the > ISDN B-Channel, but they kept the "top-speed" down at 56kbps (I suspect > because some of the US telephone network still runs at 56kbps). > > As to whether they should call it 33.2k, it depends on your perspective. > The PC sends data at 33.2, but the ISDN sends data at 56k. Ask any > marketing person whether you'll sell more 56K modems or 33.2k modems! > > Best wishes > > Chris Jaecker --------------------------------------------------------------------- To unsubscribe, mail [EMAIL PROTECTED] with the line: 'unsubscribe vnc-list' in the message BODY See also: http://www.uk.research.att.com/vnc/intouch.html ---------------------------------------------------------------------
